Jean L. Turner

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Hidden from optical view in the starburst region of the dwarf galaxy NGC 5253 lies an intense radio source with an unusual spectrum which could be interpreted variously as nebular gas ionized by a young stellar cluster or nonthermal emission from a radio supernova or an AGN. We have obtained 11.7 and 18.7 µm images of this region at the Keck Telescope and(More)
Vibration measurements of the linear accelerator structures in the SLC linac show a 1 micron rms vertical motion. This motion reduces to 0.2 micron rms motion when the cooling water to the accelerator structures is turned off. The quadrupoles have 250 nanometer rms vertical motion with the accelerator structure cooling water on and 60 nanometer motion with(More)
Little is known about the origins of globular clusters, which contain hundreds of thousands of stars in a volume only a few light years across. Radiation pressure and winds from luminous young stars should disperse the star-forming gas and disrupt the formation of the cluster. Globular clusters in our Galaxy cannot provide answers; they are billions of(More)
We present a three-dimensional data cube of the K-band continuum and the Br γ , H 2 S(0), and S(1) lines within the central 18. 5 × 13. 8 (520 pc × 390 pc) region of NGC 6946. Data were obtained using OSIRIS, a near-infrared Integral Field Spectrograph at Keck Observatory, with Laser Guide Star Adaptive Optics. The 0. 3 resolution allows us to investigate(More)
23 (ref. 26). 30 Dor is 200 times larger and 100–1,000 times less dense than the supernebula in NGC5253, and its exciting star cluster R136 is 10–100 times less massive than the cluster in NGC5253 (ref. 27). The escape velocity for 30 Dor is less than the thermal sound speed of 10 km s 21 so its gas motions are determined by winds and turbulence rather than(More)
We have imaged emission from the millimeter lines of eight molecules—C 2 H, C and SO—in the central half-kiloparsec of the nearby spiral galaxy IC 342. The 5 00 ($50 pc) resolution images were made with the Owens Valley Millimeter Array. Using these and previously published CO and HCN images, we obtain a picture of the chemistry within the nuclear region on(More)
A model-bssed beam orbit simulation program has been used successfully to analyze the beam energy errors 'at the two-mile linear accelerator during commissioning of the SLC system. Thii simulation program has also been used to develop a nondestructive beam energy error monitoring system. The method of tUdyBi8, the simulation program, and a beam energy(More)
GaAs photocathodes have been in use for generating high intensity polarized electron beams (up to a peak current of 6 A in 2 ns pulses) for the SLC high energy physics program. If the quantum efficiency (measured at low light intensities) of a GaAs photocathode is below a certain level, the maximum photoemitted charge is found to be limited by the intrinsic(More)
We present high resolution (∼ 5 ′′) maps of the J = 1-0 transitions of 13 CO and C 18 O towards the nucleus of NGC 6946, made with the Owens Valley Millimeter Array. The images are compared with existing 12 CO(1-0) maps to investigate localized changes in gas properties across the nucleus. As compared to 12 CO, both 13 CO and C 18 O are more confined to the(More)
Gas clouds in present-day galaxies are inefficient at forming stars. Low star formation efficiency is a critical parameter in galaxy evolution: it is why stars are still forming nearly fourteen billion years after the Big Bang 1 and why star clusters generally do not survive their births, instead dispersing to form galactic disks, halos, or bulges 2. Yet(More)